What size carb should you use in a 80cc 4 stroke moped?

For an 80cc 4 stroke moped, a carburetor size of 18-20mm should be adequate. This size carburetor will provide the engine with enough air and fuel to run efficiently. It is important to choose the right size carburetor for your engine, as too small of a carburetor can restrict airflow and cause the engine to run lean, while too large of a carburetor can cause the engine to run rich and waste fuel.